Generate Plant with 6dof constraint. Shaking and Performance

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Roman
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Joined: Wed May 13, 2015 3:33 pm

Generate Plant with 6dof constraint. Shaking and Performance

Post by Roman »

Hi
I'am traing to simulate a forest.
One tree consist of body (btCylinder) and 60 branches (btCylinder), connected to body with 6dof spring constraint.
I've generated 100 trees and simulation time step is >200ms. Using ForkLiftdemo with sequential impulse solver.
100 trees = 6100 objects and 6000 6dof constraints.
Is it too many to simulate in bullet?
25 trees is ok for perfomance. 25ms for step.

Another problem is that follen trees cant stop moving. It creep and branches between body and ground not calm down.
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Erwin Coumans
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Re: Generate Plant with 6dof constraint. Shaking and Perform

Post by Erwin Coumans »

Are you using the btGeneric6DofSpring2Constraint, new in Bullet 2.83?

Are those timings of an optimized build (-O2, 'release' mode)?

'shaking' could be due to differences in masses (mass ratio), or perhaps because you use the btGeneric6DofConstraint instead of btGeneric6DofSpring2Constraint.

Can you re-create the setup using a modified example, such as Bullet/examples/Constraints/ConstraintDemo.cpp?

We might give some advices, based on your shared example.
Thanks!
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